High-Mobility Satellite-UAV Communications: Challenges, Solutions, and Future Research Trends

Due to their fast deployment and high flexibility, unmanned aerial vehicles (UAVs) are regarded as vital enablers of various applications that include emergency rescue, telecommunications, delivery of supplies, and more. In order to connect UAVs to a core network anywhere, satellite communications is expected to provide wider backhaul coverage compared to ground wireless communications. Although UAV Communications has been studied in many technical works, high-mobility satellite-UAV communications has not been investigated well. Specifically, physical layer operations of the high-mobility satellite-UAV communication system are affected the most by high-mobility environments. In this article, we focus on the physical layer operation problem in satellite-UAV communications from three perspectives: time-varying channel estimation, the high-mobility transceiver, and high-mobility multiple access. Related key technologies, existing works, open problems, and the next development direction are introduced and surveyed. Furthermore, our proposed scheme is also discussed. Overall, this article aims to help readers understand challenges, solutions, and future research trends regarding physical layer operation issues on high-mobility satellite-UAV aerial communications.